/*
 *
A(int)
B(void)

 */

#include <iostream>
using namespace std;
class A{
	private:
		int m_data;
	public:
		A(int data){
			cout <<"A(int)" << endl;
			m_data = data;
		}
};
class B{
	private:
		A m_a;
	public:
		B(void):m_a(123){
			cout <<"B(void)" << endl;
		}
};
int main(void){
	B b; //一定会去构造成员对象m_a , 未指定如何构造，系统去调用m_a的无参构造函数
	return 0;
}
